The present invention relates to panel roof construction. Typically, the roof panels are of the sandwich construction, including a central layer or core of rigid plastic foam, an outer surface (preferably metal such as aluminum or steel), and an undersurface which may be decorative, if desired. Panels of the sandwich-type construction have been used in building construction, both for roofs and for walls, and they have the advantage that they have good structural and insulating properties while providing reasonable cost. The outer surface of the panels provides the roof membrane, so that there is no need to apply special roofing material.
Panel roofs have in the past, however, suffered from one principal disadvantage--namely, some leakage of water has occurred at the joints. The joints may be waterproof during initial construction, but it will be appreciated that there is substantial expansion and contraction of the individual panels when exposed to weather, and this has a tendency to rupture or break seals which have previously been used for the joints.
The present invention has as a principal object, the provision of a panel roof construction with joints which allow for normal expansion and contraction of the roof panels, yet which maintains a weatherproof joint between adjacent panels. I have realized that there are two different types of joints in a panel roof construction, and each presents its own problems in effecting a long-lasting seal. One type of joint runs along the fall line, and I refer to this as a "longitudinal" joint. The second type of joint extends transverse of the fall line, and I refer to this as a "transverse" joint. Briefly, according to the present invention, the longitudinal joints between adjacent panels are placed to coincide with the placement of roof trusses. Preferably, the roof trusses are made by joining two C-shaped channel members to form a single beam with a longitudinal slot extending along the longitudinal roof joint. A generally T-shaped metal extrusion (called a retainer strip or covering extrusion) is placed along the longitudinal joint with the arms of the "T" shape overlapping the edges of adjacent panels, and with the base of the T providing a stiffener element for the extrusion and extending into the joint between the panels.
Butyl mastic tape caulk or other sealing means is provided on the outer extremities of the arms of the T, the lower portion of these tapes being provided with a release strip for protection until they are applied. When the release strip is removed, and the extrusion assembled to the joint, it is held in place by means of threaded fasteners extending between the panels, the edges of which are spaced, and received in the longitudinal slot of the truss. Thus, this extrusion acts both to seal the longitudinal joint and to retain the panels in place. This type of joint allows the top skin of the roof panels to bow as it heats in the sun, while maintaining a seal along the longitudinal joints.
The transverse joint is provided by a tongue-in-groove construction of the panels. The upper edge of the lower panel is reduced in depth to provide the tongue. The groove extends along the lower edge of an upper panel, transverse to the fall line, and it is formed by extending the upper and lower skin materials beyond the foam core, and turning them back on one another. A narrow strip of resilient plastic foam is secured to the lower surface of the upper skin material forming the groove. This flexible foam strip is thus interposed between the overlapped outer metal surfaces, thereby forming a shingled or lapped construction, but with the outer skin material of the upper panel being spaced away from the outer skin material of the lower panel. This spacing breaks what would otherwise form a capillary between the two panels for water seepage. Further, it provides an area for effecting a caulk seal, and still further, the flexible strip itself forms a seal. The shingled relation of the outer skin is very important to achieve good drainage from the start. A Fiberglas batt may be inserted in the groove prior to assembly for a still more effective seal.
If conditions permit the transverse joint to be formed at the manufacturer's location, rivets may be used to secure the skin extensions of the upper panel to the tongue of a lower panel, in which case it is not necessary to caulk the lapped exterior seal.
The present invention thus provides a panel roof construction which is strong, has good thermal insulating properties and is convenient to assembly, yet which is economical and has long-lasting weatherproof seals along both the transverse and the longitudinal joints.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.